1. Field of the Invention
The present invention relates to an In-Plane Switching (IPS) mode liquid crystal display (LCD) device and, more particularly, to an IPS-LCD device with a color filter formed on an array substrate.
2. Description of the Related Art
In a conventional twisted nematic LCD (TN-LCD) device, liquid crystal molecules are twisted between two facing electrodes respectively formed on two substrates, in which an electric field is generated in an approximately vertical direction to the plane of the two substrates. To achieve the aim of wide viewing angle, an in-plane switching mode LCD (IPS-LCD) device has been proposed, in which common electrodes and pixel electrodes are formed on the same substrate (TFT array substrate) and an in-plane electric field therebetween is generated to rearrange the liquid crystal molecules along the in-plane electric field. Accordingly, the IPS-LCD device has been used for improving viewing angle, contrast ratio and color shift.
FIG. 1A is a top view showing a conventional IPS-LCD device. FIG. 1B is a sectional diagram along line Axe2x80x94A shown in FIG. 1A. The IPS-LCD device has an array substrate 10, a color filter (CF) substrate 12, and a liquid crystal layer 14 formed in a gap between the two parallel substrates 10 and 12. On the array substrate 10, a plurality of traverse-extending scanning electrodes 16 and a plurality of lengthwise-extending signal electrodes 18 are arranged in a matrix form to define rectangular-shaped pixel areas 20. Also, in each pixel area 20 a strip-shaped pixel electrode 22 is disposed between two strip-shaped common electrodes 24 which are the branches of a common line 24A, and both of the pixel electrode 22 and the common electrode 24 are parallel to the signal electrodes 18. Moreover, each pixel area 20 has a thin-film transistor (TFT) structure 26 with a drain electrode electrically connected to the pixel electrode 22. When a voltage is applied to electrodes, an in-plane electric field is produced between the pixel electrode 22 and the common electrode 24.
In processing the array substrate 10, the scanning electrodes 16 and the common electrodes 24 are patterned on the same level plane, and then covered by a gate insulating layer 17. Next, the signal electrodes 18 and the pixel electrodes 22 are patterned on the gate insulating layer 17. Thereafter, a first orientation layer 19 is formed to cover the entire surface of the array substrate 10. On the CF substrate 12, a plurality of black matrix layers 13, a color resin layer 15, and a second orientation layer 21 are successively stacked and faced to the liquid crystal layer 14. This black matrix layer 13 is provided so as to hide the TFT structure 26, the scanning electrode 16, the signal electrode 18, and the like with respect to the external field of this TFT structure 26.
However, in the above structure, the common electrodes 24 and the pixel electrodes 22 are opaque to result in a low transmittance. Also, the common electrodes 24 adjacent to the signal electrode 18, serving as shielding electrodes, are required to avoid a lateral field between the pixel electrode 22 and the signal electrode 18. Therefore, in the area I, an aperature ratio is less than desired. Furthermore, in the area II, since a short by coupling the common line 24A and the scanning electrode 16 in the manufacturing process is often generated, the yield is reduced.
The present invention is an IPS-LCD device having a color filter on the array substrate and a common electrode overlapping the signal electrode to solve the above-mentioned problems.
The in-plane switching mode liquid crystal display (IPS-LCD) device has a lower glass substrate and an upper glass substrate disposed parallel to each other. A plurality of transverse-extending scanning electrodes and a plurality of lengthwise-extending signal electrodes are patterned on the lower glass substrate to define a plurality of pixel areas. In each pixel area, at least a lengthwise-extending pixel electrode and at least two lengthwise-extending common electrodes are formed on the same level plane of the lower glass substrate, wherein the pixel electrode is disposed at the interval between the common electrodes. Also, a color resin layer is sandwiched between the signal electrodes and the common electrodes. Moreover, the common electrode is located over the signal electrode across two adjacent pixel areas.
Accordingly, it is a principle object of the invention to provide the color filter on the array substrate.
It is another object of the invention to avoid a lateral field generated between the signal electrode and the pixel electrode.
Yet another object of the invention is to prevent light leakage between the signal electrode and the common electrode.
It is a further object of the invention to achieve a high aperture ration in the IPS-LCD device.
Still another object of the invention is to reduce the coupling between the common electrode and the scanning electrode.
Another object of the invention is to avoid electron charges remaining on the electrodes so as to prevent the image-sticking problem.
It is an object of the invention to increase the yield.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.